The present invention relates to a ribbon cassette, or cartridge, of the type which can be inserted into a typewriter or similar office machine and which includes a ribbon which is brought from a supply reel and past guides through a printing station in the machine, and which is then wound onto a takeup reel.
In typewriters or similar office machines employing ribbon cassettes, use is generally made either of textile ribbons which are transported from one reel to the other or in the form of an endless loop several times past the printing station, or of single-use carbon ribbons which pass through the machine only one since each surface portion of such a ribbon can be used for printing only once, or of multi-use carbon ribbons which also pass through the machine only a single time but in which individual surface sections furnish multiple imprints. In the case of textile ribbons, the magnitude, or length, of each step is not so important since each surface section of the ribbon is used several times. In the case of single-use carbon ribbons, the advancing step must equal the width of a whole character, while the multi-use carbon ribbons require a drive for the ribbon which produces a smaller advancing step so as to provide economical utilization of the ribbon.
To switch a ribbon drive automatically, to the respective mode of operation required, simply by inserting the particular ribbon cassette, the cassette used in a prior art drive disclosed in German Auslegeschrift [Published Patent Application] No. 1,611,454 has a feature which changes the length of the transporting step in dependence on the type of ribbon disposed therein. A transporting roller disposed at the side of the machine is here connected with a translatory gear mechanism which is positively switched by the cassette for changing the length of the transporting step in the cassette so that a longitudinal transporting step is produced which in one case corresponds to the width of type which has been struck and in the other case causes the type imprints on the ribbon to overlap.
Furthermore, U.S. Pat. No. 4,231,667 discloses a drive for a ribbon disposed in a cassette wherein the ribbon is advanced by driving a feed roller. This feed roller is coupled with a device in the machine side for generating a ribbon advancing step of a length which differs in dependence on the type of ribbon employed. On the driven side, this device has two gear members which rotate at respectively different peripheral speeds and only one of which can be coupled with the feed roller disposed in the cassette when this cassette is placed onto the machine. Coupling of a toothed wheel which is firmly connected with the cassette with another toothed wheel associated with the machine is not always possible without malfunction since the parts to be coupled will not always be in a precise position with respect to one another.
Although a removable cassette for a carbon ribbon for typewriters and other office machines disclosed in German Offenlegungsschrift [Laid-Open Patent Application] No. 2,553,329 has a toothed wheel which cooperates with the outermost turn of a winding reel and which is driven by a drive element in the machine, this prior art device permits only a constant length ribbon transporting step and does not provide a way for differently driving the ribbon in dependence on the type of ribbon employed. Also, this prior art arrangement does not provide optimum utilization of the storage area for the supply and takeup reels since the toothed roller and the pivot lever for the takeup reel are also disposed in the storage area.